Recently an alloy called Ce3Al was successfully synthesized under normal atmospheric temperature and high pressure in International Center for New-Structured Materials in Zhejiang University for the first time. Doctor Qiaoshi Zeng, the first author of ’Substitutional Alloy of Ce and Al’, has published his results in Feb 2nd’s edition of Proceedings of the National Academy of Science, USA.

Rare-earth metals, called the "vitamin of modern industry", are generally used to develop the new materials such as ferromagnetic, magnetostriction material, fluorescence, or catalyst. Cerium is the first rare-earth metal including ambient 4f electron, so it becomes one of the hot fields in Physics and material science; while aluminum can combine with the similar metals to form a series of aluminum alloys, so it plays an important role in people’s life. However, according to Hume－Rothery rules, Cerium and aluminum are two incompatible elements, which means they can not generate a Substitutional Alloy but a lot of compounds, since their atomic radiuses and electro negativities are quite different.

In collaboration with Kuang-piu Lecture Professor H.K. Mao, Doctor Qiaoshi Zeng followed his supervisor Profess Jianzhong Jiang’s instruction to use the synchrotron X-ray diffraction to study the behavior of Ce3Al under high pressure. Synchrotron X-ray diffraction, Ce L3-edge absorption spectroscopy, and ab initio calculations revealed that the pressure-induced Kondo volume collapse and 4f electron delocalization of Ce reduced the differences between Ce and Al and brought them within the Hume-Rothery (HR) limit for substitutional alloying. The alloy remained after complete release of pressure, which was also accompanied by the transformation of Ce back to its ambient 4f electron localized state and reversal of the Kondo volume collapse, resulting in a non-HR alloy at ambient conditions.

This research finding shows that new alloys with other incompatible elements can be synthesized by adjusting the pressure. These new alloys may possess interesting and useful mechanical, electronic, and magnetic properties. After the dissertation was published, NEWS FROM THE WORLD OF MATERIALS organized a highlight report immediately.